How do I get computers to build and attack like on original starcraft campeign??

Run an AI script for the computer. One of the insane or custom should work well, just make sure you choose one that is meant for the computer's race.

EDIT: I know there are topics in Assistance that cover this question in detail, but search keeps returning a blank page no matter what I enter, and google keeps pulling up stuff not actually related to this.

Post has been edited 1 time(s), last time on Apr 19 2009, 4:43 am by Elvang.

Keep In mind, however, that the Insane and Custom Computers Cheat.

Other AI scripts do not, I beleive.

All AIs cheat at least regarding intel. They always know where you are and what you have.
And I sincerely doubt that custom has another cheat built in, because that's the AI that is used in melee games.
Insane however, has a built-in money cheat.

Blizzard made AIs for (almost) every campaign mission. Some of them do special things, for example build nukes. If you make a map that is similar to a campaign mission you might want to use the respective AI.